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block-backend-common.h (3192B)

      1 /*
      2  * QEMU Block backends
      3  *
      4  * Copyright (C) 2014-2016 Red Hat, Inc.
      5  *
      6  * Authors:
      7  *  Markus Armbruster <armbru@redhat.com>,
      8  *
      9  * This work is licensed under the terms of the GNU LGPL, version 2.1
     10  * or later.  See the COPYING.LIB file in the top-level directory.
     11  */
     12 
     13 #ifndef BLOCK_BACKEND_COMMON_H
     14 #define BLOCK_BACKEND_COMMON_H
     15 
     16 #include "qemu/iov.h"
     17 #include "block/throttle-groups.h"
     18 
     19 /*
     20  * TODO Have to include block/block.h for a bunch of block layer
     21  * types.  Unfortunately, this pulls in the whole BlockDriverState
     22  * API, which we don't want used by many BlockBackend users.  Some of
     23  * the types belong here, and the rest should be split into a common
     24  * header and one for the BlockDriverState API.
     25  */
     26 #include "block/block.h"
     27 
     28 /* Callbacks for block device models */
     29 typedef struct BlockDevOps {
     30 
     31     /*
     32      * Global state (GS) API. These functions run under the BQL.
     33      *
     34      * See include/block/block-global-state.h for more information about
     35      * the GS API.
     36      */
     37 
     38     /*
     39      * Runs when virtual media changed (monitor commands eject, change)
     40      * Argument load is true on load and false on eject.
     41      * Beware: doesn't run when a host device's physical media
     42      * changes.  Sure would be useful if it did.
     43      * Device models with removable media must implement this callback.
     44      */
     45     void (*change_media_cb)(void *opaque, bool load, Error **errp);
     46     /*
     47      * Runs when an eject request is issued from the monitor, the tray
     48      * is closed, and the medium is locked.
     49      * Device models that do not implement is_medium_locked will not need
     50      * this callback.  Device models that can lock the medium or tray might
     51      * want to implement the callback and unlock the tray when "force" is
     52      * true, even if they do not support eject requests.
     53      */
     54     void (*eject_request_cb)(void *opaque, bool force);
     55 
     56     /*
     57      * Is the virtual medium locked into the device?
     58      * Device models implement this only when device has such a lock.
     59      */
     60     bool (*is_medium_locked)(void *opaque);
     61 
     62     /*
     63      * I/O API functions. These functions are thread-safe.
     64      *
     65      * See include/block/block-io.h for more information about
     66      * the I/O API.
     67      */
     68 
     69     /*
     70      * Is the virtual tray open?
     71      * Device models implement this only when the device has a tray.
     72      */
     73     bool (*is_tray_open)(void *opaque);
     74 
     75     /*
     76      * Runs when the size changed (e.g. monitor command block_resize)
     77      */
     78     void (*resize_cb)(void *opaque);
     79     /*
     80      * Runs when the backend receives a drain request.
     81      */
     82     void (*drained_begin)(void *opaque);
     83     /*
     84      * Runs when the backend's last drain request ends.
     85      */
     86     void (*drained_end)(void *opaque);
     87     /*
     88      * Is the device still busy?
     89      */
     90     bool (*drained_poll)(void *opaque);
     91 } BlockDevOps;
     92 
     93 /*
     94  * This struct is embedded in (the private) BlockBackend struct and contains
     95  * fields that must be public. This is in particular for QLIST_ENTRY() and
     96  * friends so that BlockBackends can be kept in lists outside block-backend.c
     97  */
     98 typedef struct BlockBackendPublic {
     99     ThrottleGroupMember throttle_group_member;
    100 } BlockBackendPublic;
    101 
    102 #endif /* BLOCK_BACKEND_COMMON_H */